The invention relates to a method for predictive open-loop and/or closed-loop control of an internal combustion engine using control variables according to a model of the internal combustion engine, said model having characterizing variables, and according to a closed-loop control circuit for the control variables, wherein                in the method, the control variables of the internal combustion engine are set in an open-loop controlled or a closed-loop controlled manner and the method comprises the following steps:        measuring actual values and specifying desired values of the characterizing variables of the internal combustion engine, and also optionally in dependence upon boundary conditions and/or environmental conditions and/or aging conditions. The invention also specifies a device for predictive open-loop control and/or closed-loop control of the internal combustion engine, said device being embodied for implementing the method. Furthermore, the invention specifies to an internal combustion engine having the device for predictive open-loop and/or closed-loop control of the internal combustion engine.        
The closed-loop control of characterizing variables can be performed according to a model of the internal combustion engine, said model having the characterizing variables, and according to a closed-loop control circuit having the control variables, wherein the closed-loop control is performed within the scope of a model-based predictive closed-loop control in which the characterizing variables of the model of the internal combustion engine are calculated and the control variables of the internal combustion engine are set in a predictive closed-loop controlled manner. Predictive closed-loop control concepts are associated with the class of the model-based closed-loop control methods and generally render it possible to make a prediction in the future for the closed-loop control circuit, namely for a so-called prediction horizon. Such predictive closed-loop control concepts have proven reliable since they render it possible within the scope of the prediction of the system behavior to achieve an optimized closed-loop control; this can already take into account information regarding future operating behavior of the system. This has the result that desired value specifications and also boundary conditions for a closed-loop control circuit can be set and/or maintained in an optimized manner. Altogether, as a consequence it is possible to achieve improved closed-loop control quality and/or a more rapid closed-loop control procedure. It is possible to define more complex closed-loop control targets and systematically to take into account limitations in control variables or physical variables of the system.
However, in the case of such predictive closed-loop control concepts and other predictive closed-loop control concepts, the comparatively complex computing outlay is regularly problematic with the result that predictive closed-loop control concepts have hitherto only been offered for part components of an engine of an internal combustion engine. The embodiment of a suitable model of the part component of an engine is significant for the success of a predictive closed-loop control concept. Hitherto, it was in particular not possible to realize optimized predictive closed-loop control concepts in real time on an engine control unit for the global open-loop control and closed-loop control of the entire internal combustion engine, for example also taking into account a component of an exhaust gas aftertreatment having suitable quality requirements for the closed-loop control and in real time.
To the extent that predictive closed-loop control concepts are known for diesel engines, these are limited to greatly simplified models of a system, in other words in particular to only linearized system models that moreover are embodied in a static manner or only with insufficient timescales, in particular process times and/or process scales. Moreover, hitherto known predictive closed-loop control concepts do not take into account sufficient boundary conditions—hitherto sufficient use of characteristic diagram structures has not been made. This results in both a comparatively large outlay for extracting parameters of the characteristic diagrams as well as to these closed-loop control concepts being comparatively inflexible, for example if the internal combustion engine is changed or the environmental conditions are changed. For this reason, greatly linearized models that are based on characteristic diagram factors and correcting factors and are used for predictive closed-loop control approaches do not render possible optimal operation of the entire system of an internal combustion engine, in particular a diesel engine.
Closed-loop control concepts such as by way of example those disclosed in DE 10 2011 013 481 A1 and EP 1 864 012 B1 suffer from such disadvantages and other disadvantages.
DE 10 2011 013 481 A1 thus is only limited to a part aspect of a diesel engine; namely an actuator of the internal combustion engine in which the actuator is set in dependence upon the entire gas mass, the oxygen content, the desired entire gas mass and the desired oxygen content. Such a stark reduction in the number of actuators is not appropriate for the holistic (global) predictive closed-loop control approach for the entire internal combustion engine.
EP 1 864 012 B1 relates to a multivariable model-predictive closed-loop controller for fuel- and/or air-related parameters taking into account a central optimizing algorithm that functions with state limitations and/or actuator limitations. Moreover, the excessive use in this case of characteristic diagram structures is disadvantageous for the closed-loop control concept.
It would be desirable to provide a holistic model-based predictive closed-loop control of an internal combustion engine that renders it possible to control in a closed-loop manner the entire internal combustion engine, preferably in a global manner, in particular taking into account components of an exhaust gas aftertreatment within the scope of a model-based predictive closed-loop control in real time on an engine control unit (ECU). The predictive closed-loop control concept should take into account the non-linearities of the system of the internal combustion engine or the model of the internal combustion engine. Hitherto non-linear model-predictive closed-loop controllers have proven to be incapable of functioning in real time on an engine control unit (ECU) for an entire model of an internal combustion engine owing to their being comparatively very complex. The above mentioned greatly simplified models are however not practicable, at least not globally over the entire operating range.